Vehicle security systems are widely used to deter vehicle theft and perform various security-related vehicle functions. A typical vehicle security system includes a controller having a receiver connected thereto. The controller may perform security-related functions, such as locking/unlocking doors, or switching between armed and disarmed modes responsive to signals received from one or more remote transmitters. When in the armed mode, the controller may generate an alarm indication at the vehicle responsive to a vehicle security sensor indicating a vehicle security breach. The remote transmitters are typically carried by the owner of the vehicle.
Some vehicles are equipped with remote keyless entry (RKE) features to permit a user to remotely lock and unlock the vehicle doors using a small handheld transmitter. One class of RKE arrangements provides a driver door priority unlock feature. The driver door priority unlock feature operates as follows. The user presses a door unlock button on the handheld transmitter to send a first signal to a receiver at the vehicle. In response, a first controller output is operated which causes only the driver's door to unlock. If the user wishes to unlock all of the vehicle doors, the same unlock button is pressed a second time and within a predetermined time of its first pressing. The receiver causes a second control output to operate which thereby unlocks all of the vehicle doors. U.S. Pat. No. 5,850,173 to DiCroce et al., for example, discloses such a vehicle RKE arrangement with the driver door priority unlock feature.
Other vehicles include a more basic RKE arrangement whereby all of the vehicle doors are unlocked based upon receiving an unlock signal from the remote transmitter. For these vehicles, only a single output is used to unlock all of the vehicle doors.
It is quite common to upgrade RKE factory installed equipment with an aftermarket security system to provide additional security features. A typical aftermarket vehicle security system includes two outputs and control circuitry to be compatible with the two-output driver door priority unlock RKE equipment described above. Of course, such an aftermarket vehicle security system will also be compatible with the basic RKE equipment which only unlocks all of the vehicle doors. The second output, however, will remain unused when the aftermarket security system is installed with basic RKE equipment. It is often desired to perform a number of remote control functions to enhance the user's convenience. Accordingly, it is somewhat inefficient to have the second output remain unused.